Figure 8-1 shows that an HVDCP source is first qualified as a DCP source in the USB BC1.2 standard detection stage, then qualified in the following HVDCP detection stage as an HVDCP source. When the HVDCP is first qualified as a DCP, the charger sets an IINDPM limit of 3.25A. The IIDPM is then updated to the HVDCP limit of 1.5A after the HVDCP handshake completes. In some cases the higher IINDPM limit of 3.25A may interfere with the source's ability to transition to 9V or 12V if the transition is attemped before the IINDPM is updated to 1.5A.

The recommended procedure for enabling detection of HVDCP sources is completed in the following steps:

• Before adapter insertion, the charger is configured with AUTO_INDET_EN = 1 and HVDCP_EN = 0. EN_12V and EN_9V are set as desired for the system.
• When an adapter is inserted, it will be detected as SDP, CDP, DCP or a Non-Standard adapter and an I²C interrupt is sent to the host. If any detection other than DCP is made, the host proceeds as usual.
• If the adapter is detected as DCP (VBUS_STAT[3:0] = 0011), the host first changes the Input Current Limit register to 1.5A and then changes HVDCP_EN = 1.
• After HVDCP detection is complete, the host sets HVDCP_EN = 0 to disable HVDCP support in preparation for the next input source detection sequence.